The present invention relates to a new and improved arrangement at a stand for an optical observation device.
Generally speaking, the arrangement of the present development is of the type comprising a stand having an upright or stand column, a pivotable arm mounted at the stand column and provided with a counterweight, a support arm, a plurality of rotary and brake bearings and a hinge parallelogram. The hinge parallelogram is structured such that at its front region it is capable of accommodating an optical observation device, in particular a surgical microscope.
Adjustable supports or stands for an optical observation instrument are well known to the art, as evidenced for instance by the commonly assigned U.S. Pat. Nos. 3,762,796, granted Oct. 2, 1973, 3,762,797, granted Oct. 2, 1973, 3,887,267, granted June 3, 1975 and 3,891,301, granted June 24, 1975.
In particular, in Swiss Pat. No. 548,568 and the corresponding U.S. Pat. No. 3,891,301 there is disclosed a support device for a surgical microscope, which is constructed as a stand and equipped with a number of rotary and brake bearings. With this prior art construction it is known to arrange at a stand or upright column a pivotable arm constructed as a balance and pivotable about a first horizontal axis. At the pivotable arm there is arranged to be displaceable and fixedly positionable a first balancing or compensation weight. At the upper region of the pivotable arm there is provided an intermediate element constructed as a balance beam, at which there is arranged at one side a hinge parallelogram structured for the reception and attachment of the surgical microscope and at the other side a further displaceably mounted balancing or compensation weight. This balancing or compensation weight is arranged to be cantilevered to such a degree and possesses a mass such that it corresponds to the weight of the suspended microscope. Such arrangement of the compensation or balancing weight at the pivotal arm and the intermediate element are particularly suitable for support devices of massive construction which are not subject to any spatial limitations.